;(function (w,undefined) {
   var strTool = {
       "isEmpty":function (str) {
            return str.length == 0?true:false;
       },
       //...........
   };

        //对两个数求和
        w.add=(a,b)=>{
          return a+b;
        };

        w.jian = function(a,b){
          return a-b;
        };


   w.strTool = strTool;

})(window);
